Leaf form and stomatal characteristics play an important part in the strategy of tall fescue (Festuca arundinacea Schreb) to limit water losses. Transpiration rates of artificially rolled leaves measured by potometer at varying wind velocities support this assertion.

The effect of FeSO₄.7H₂O, Fe₂(SO₄)₃.9H₂O, disodium salt of ethylene-diaminotetraacetic acid, dihydrate (EDTA) and N-(2-acetamido) iminodiacetic acid (ADA) and their combinations on the androgenesis was studiedin vitro in tobacco (cv. White Burley) and datura (Datura innoxia Mill.). Simultaneously the reversibility and irreversibility of the morphogenic process leading to the conversion of the pollen embryoid into complete plant was followed.
Complete plants developed in anthers on media with trivalent iron, chelated trivalent iron, chelated bivalent iron, bivalent iron in the presence of ADA and of media with EDTA. The number of androgenic plants in anthers increased in the following order: Fe₃₊ < Fe₃₊ EDTA ≦ ≦ EDTA < Fe²⁺ EDTA. The marked brown colour of cultured anthers was due to the presence of trivalent iron in the medium. The androgenic development was most rapid on the medium containing only trivalent iron, slower on media with chelated iron and slowest on medium with EDTA. The viability of cultures with complete plants decreased in the reverse order. No complete plants grew on media without trivalent iron and without EDTA and on media containing only bivalent iron whereas globular embryoids arose and developed continuously on these media. The anthers reacted in the same way on both complete and minimal media. Isolated embryoids formed complete plants in corresponding variants on complete media only.
The development of pollen embryoids into complete plants was stopped by the transfer of globular and torpedo-shaped embryoids from medium with EDTA to the medium without EDTA. Isolated greenish cotyledonar embryoids continued to grow even on the medium without EDTA.

The data of Rowet al. (1961) on endogenous indoleacetylaspartic acid in tomato plants were reexamined. It was shown that two indole compounds were present in ethanolic extract of tomato stems and leaves. The predominating substance was concluded to be N-malonyltryptophan on account of its UV- and IR-spectra, colour reactions with the Ehrlich and Salkovski reagents and products of acidic and alkaline hydrolyses. The chemical nature of the second indole compound remained unknown. It differed from N-malonyltryptophan, N-aeetyltryptophan, indoleacetylaspartic acid and indoleacetic acid and may result from non-enzymatic transformation of N-malonyltryptophan.

Nitrate reductase (NR) activity of bothPisum sativum L. cv. Bonneville andTriticum aestivum L. cv. Sonalika seedlings was influenced by the phytochrome system. Short durations of "red" irradiation (R) increased extractable levels of NR whereas subsequent short "far-red" irradiation (FR) partially inhibited the R modulated increases. Qualitatively, a negative correlation existed between thein vitro NR activities andin vivo phytochrome levels inPisum. "Blue" irradiation (B) also increased extractable levels of NR inTriticum. A partial action spectrum study made by exposing excised etiolated leaves ofTriticum and shoot apices ofPisum revealed a maximum increase in extractable NR activities and tissue nitrate level (inTriticum) at 656 nm. A partial action spectrum for the extracted enzyme ofTriticum indicated that at 700 nm the level of activity was increased (as compared to dark controls) more than by R (656 nm), FR (725 nm) or B (425 or 450 nm) irradiation, although all wavelengths used increased NR activity.

In the natural monsoon environment, the leaves of Bala and Jaya cultivars experienced more than 10 per cent LWD for about 8 and 6 1/2 h in the diurnal cycle, respectively. The maximum LWD of around 14 per cent occurred between 14.30 to 15.30 at the time of minimum relative humidity (EH) and maximum air temperature (Ta). On the other hand, under controlled environment conditions, LWD values of both the cultivars remained below 10 per cent in the entire diurnal cycle. There was a close relationship between LWD and Ta (r = 0.90 for Bala and 0.91 for Jaya) as well as RH (r = -0.95 for Bala and -0.85 for Jaya). The results suggested that RWC values obtained on an interval of 30 min were not enough to observe more than the general trend as a complete recovery of stress achieved within 25 min of rewatering the stressed leaves. Calculations indicated that the determination of LWD with the techniques using excised leaf are likely to incur error as rice leaf may loose water at a rate of 0.3 MPa min^-1.

The degree of tolerance of two crown gall tumors and leaf calli ofArabidopsis thaliana to BUdR was compared. The nopaline producing teratoma tumor tolerated BUdR in concentration as high as 2.10^-4 M. The tolerance of octopine producing unorganized crown gall tumor to BUdR was lower, but both exceeded significantly the degree of tolerance to BUdR of untransformedA. thaliana calli, where 10^-5 M BUdR already show some inhibitory effect on the growth rate.

The effects ofo-, m- andp-hydroxyphenylacetic acids on total peroxidase activity and isoperoxidase patterns of wheat coleoptile sections were studied.o-andm-HOPA reduced the total peroxidase activity whilep-HOPA increased it. Electrophoresis in polyacrylamide gel revealed thato- andm-HOPA diminish the intensity of some anodic and cathodic bands, but thatp-HOPA increases anodic and reduces cathodic isoperoxidases. These results may explain the apparently paradoxical positive effects ofp-HOPA on both growth and total peroxidase activity.

Extracts of small amounts of inflorescence material (3 lingular flowers, 3 tubular flowers, 1 receptacle with involucral bracts), obtained withn-hexane, were analysed by gas-liquid chromatography using a capillary column. The presence of terpenoids was demonstrated and differences in composition between extracts from different inflorescence parts were found.

The LpDH and NpDH activities in crown gall tumors incited byAgrobacterium tumefaciens strain C58 were followed in 7 plant species and 100 tumors were assayed in each experimental variant. The NpDH activity was found in 790 out of 800 crown galls observed. The LpDH activity was tested, after induction of tumors withA. tumefaciens strain B6-806 and 37400, in three experimental variants. The LpDH activity was found in 290 out of 300 crown galls. In the small fraction of the LpDH and NpDH negative tumors, the activity was possibly actually present, but it was below the limits of the sensitivity of the detection technique used.

Using biospecific chromatography on D-Glc-Separon-fetuin, lectins were isolated from seed albumin complexes of four cultivars ofPhaseolus vulgaris (Veltruská Saxa, Vainica Saavegra, Krupnaya sakharnaya, Olympia) andPhaseolus vulgaris ssp.aborigineus (wild form, considered to be one of the ancestors of cultivated beans). In the lectins isolated the agglutinating activity against human erythrocytes of the A, B, and O groups was estimated, as well as against trypsin-treated and non-treated rabbit erythrocytes. Further analyses involved their mitogenic activity against lymphocytes of murine spleen, their isoelectric points by isoelectric focusing in polyacrylamide gels, and eventually their immunospecific similarity with the lectins of the standard cultivar ofPhaseolus vulgaris, Veltruská Saxa.
The lectins of all taxa were mitogenic, but differed from one another in their agglutinating activity and in the number and isoelectric points of the zones, as revealed by both isoelectric focusing and immunoelectrophoresis. In the case of the cultivar Vainica Saavegra, which is a seggregating population, even the lectins of individual seed groups were different.

The content of endogenous gibberellins was estimated in leaves adjacent to the individual nodes ofBryophyllum crenatum in five ontogenetic periods (July 10, August 12, September 17, October 22, and December 8). Their content decreased from the stem base to the apex when 5 to 7 leaf pairs were developed (July 10 and August 12). Before transition to the generative state when 8 leaf pairs were formed (Sept. 17 and Oct. 22) the content of gibberellins was gradually increased in the apical leaves and decreased in the basal ones. This change resulted in the increasing gradient of leaf gibberellins from the stem base to the apex just before flowering (Dec. 8).
The content of endogenous gibberellins increases during the leaf ontogenesis up to the beginning of its senescence. This trend occurs first in the basal leaves (I -III) where the initial increase is followed by the decline in the gibberellin content. On the other hand gibberellins in leaves derived from the apical nodes (VII-VIII) only gradually increase in the course of leaf ontogenesis.

The counter-flow of³H-IAA and¹⁴C-ABA was studied in both aeropetal and basipetal arrangement in 11-cm long segments of pea epicotyls. A significant acropetal flow of¹⁴C-ABA was promoted by exogenous application of³H-IAA in the apical part of the segment together with a simultaneous promotion of its elongation growth. In the case of limited basipetal flow of¹⁴C-ABA neither the accumulation of this growth regulator on site of³H-IAA application nor a growth promotion were observed.

During high altitude acclimatization soluble sugar contents were highest in temperateArtemisia species when grown at 550 m and tropicalArtemisia species at 3600 m in the active growth phase. During the senescence in all the species the soluble sugar contents were low in plants grown at 3600 m.
The starch content was low in the leaves of the tropical and sub-temperate species when grown in the alpine zone but in the temperate species a significantly higher amount of starch was observed at 3600 m altitude.
The amount of lignin acids was lower in the tropical and sub-temperate species but higher in the temperate species when these were grown at a higher altitude.

Lethal and mutagenic effects ofN-nitroso-N-ethylurea (NEU) on the parasitic fungusCercospora beticola Sacc. was investigated. Mutation frequency increased and the number of surviving individuals (conidia) simultaneously decreased with increasing mutagen concentration and the period of its application.
Treatment ofC. beticola conidia with NEU induced 14 morphological mutants characterized by changes in pigmentation of air mycelium and substrate, excretion of the pigment into the cultivation medium and colonies morphology. A considerable proportion of morphological mutants lost their sporulation ability bothin vitro on the sporulation medium andin vivo on host leaves and became non-pathogenic. The other morphological mutants (21.4%) were pathogenic on a sensitive sugar beet cultivar Dobrovická A and on other three resistant cultivars (Maribo 1, 2, 3).
A revertant with increased pathogenity arose from the light non-pathogenic mutant. During the remonosporic isolation of the pathogenic mutants isolates were obtained characterized by a phenotype which originated during the mutagenic process.

During 6 days of pea seed germination the depletion of legumin with mol. m. 390 000 from protein bodies was observed. SDS-PAGE indicated that the legumin subunits with mol. m. 41 700 and 21 000 were prevailing. Only the former of these, probably corresponding to α-subunit, was degraded rapidly during 6 days of germination.
Water-soluble proteins (albumins) prepared from pea cotyledons were separated by preparative IEF into proteins with pI 7.1, 6.5, 6.0, 5.4, 5.0, and 4.6. During 6 days the components of albumin with pI 7.1, and 6.5 were dramatically depleted. Major fractions with pI 6.5, 6.0, and 5.4 were subjected to SDS-PAGE and their subunit composition was determined. Moreover, albumin of pea cotyledons was resolved into 13 components by SDS-PAGE. Mobilization of albumin began from the degradation of components with higher mol. m. during germination.

Crude enzyme extracts from the zones of division, elongation and differentiation of cells of primary maize (Zea mays) root show peroxidase activity but lack IAA-oxidase activity. After partial purification of the extracts by gel filtration on Sephadex G-25, the specific peroxidase activity increases almost twice and a high IAA-oxidase activity appears.
The partial purification of the enzyme extracts does not change the electrophoretic pattern of the peroxidase isoenzymes, but significantly improves the separation and the visualization of isoenzymes with IAA-oxidase activity.
The data obtained were interpreted in connection with the different modifying effect of the low molecular compounds (mainly phenolics) on the activity and the isoenzyme patterns of the peroxidase and the IAA-oxidase.

Nitrate concentration required for maximal extractable level of nitrate reductase (NR) inWolffia varies with the conditions prior to the nitrate treatment. Maximal enzyme activity is obtained at 2 mM nitrate concentration with asparagine grown plants and at 15 mM with nitrate grown. Both the level of enzyme activity and nitrate uptake by the tissue are increased by irradiation. The radiant energy induced increase in enzyme activity is not due to photosynthetic activity alone. An effect of radiant energy at the membrane level is sug gested. The extracted enzyme, which is labile, is protected and activated by NADH at 0 °C.

The male sterilants exo-3,4-methano-L-proline (MP) and cis-α-(carboxycyclopropyl)glycine (CCPG) were not converted to ethylene, eitherin vitro or in wheat coleoptile segments. Neither of these substances was able to affect IAA- and ACC-induced ethylene biosynthesis in wheat coleoptile segments to such an extent that it could explain their effect ay male sterilants.

A mathematic model of loaf water potential daily dynamics was employed to study the relationship between this characteristic and soil moisture for the speciesQuercus cerris,Acer campestre andCarpinus betulus. It was found that when evaluating the availability of soil water for a plant it is necessary to consider the vapour pressure deficit which remarkably affects the relationship between the soil moisture and leaf water potential. A quantitative description of the dependence between the leaf water potential and soil moisture enabled a physiological interpretation of the limit values of soil moisture - permanent wilting and reduced availability of soil water for the plant - as well as evaluation of the drought resistance of plants.

The capacity of pollen tubes to utilize exogenous uridine during 8 h of cultivation in shaken suspension in a sugar-mineral medium was examined by continuous and pulse labelling with³H-uridine. The increase of uptake with increasing concentration of the nucleoside indicated a saturable transport system with an approximate K_m of 9.4 × 10^-6 M and 12.5 × 10^-6M as determined in 1-h and 6-h cultures, respectively. Maximal uptake took place at the beginning of germination reaching a rate of about 2 nmol h^-1 per 1 mg of dry pollen at 0.1 mM external uridine. The uptake activity decreased with the time of pollen tube growth to less than one third during the 8-h cultivation period. Moreover, the level of radioactivity taken up initially decreased later on during continuous cultivation in the presence of³H-uridine. The uptake took place against a concentration difference and the onset and rate of uridine release depended on its exogenous concentration.
The activity of the nucleoside incorporation into RNA increased during the first 4 h of cultivation, decreasing later on. The proportion of RNA radioactivity in continuously labelled pollen tubes grew steadily during 6 h and reached 2.5% with respect to soluble pool at 0.4 μM uridine. The time course of RNA labelling was independent of uridine concentration within the range of 0.4 μM to 40 μM but this concentration rise resulted in an about fiftyfold increase of the total amount of external uridine incorporated.